Red turpentine beetle primary attraction increases linearly with (−)‐β‐pinene+ethanol dose regardless of component ratios, and no change in response with addition of high‐release frontalin

Abstract

Abstract Lure efficacy for primary attraction of red turpentine beetle, Dendroctonus valens (Coleoptera: Curculionidae: Scolytinae) observed previously in US Pacific Northwest ponderosa pine forests is (−)‐β‐pinene+ethanol > (+)‐3‐carene+ethanol > (+)‐α‐pinene+ethanol. Influence of (−)‐β‐pinene+ethanol release rates was tested with nine lures representing all combinations of three release levels for each compound in a 3 × 3 factorial design field test in Oregon. Beetle catch had a positive, linear relationship with the combined (−)‐β‐pinene+ethanol total release (or dose), resulting from higher release of either one or both compounds. Reversing component ratios, that is, 1 : 2 versus 2 : 1 with similar total doses, produced minimal changes in beetle response. Females produce frontalin with dual aggregation and sex‐pheromone functions. In another test, high‐release frontalin, defined as >1.0 mg/day release, was tested at 1.4 to 1.5 mg/day in combination with each monoterpene+ethanol lure above and their trap catch compared with (−)‐β‐pinene+ethanol lures. Presence of high‐release frontalin produced minimal changes in beetle responses.